This invention relates to a continuous wave, chemical laser. More particularly, this invention relates to a chemically pumped, atomic iodine laser in which the lasing action occurs by reason of an energy transfer reaction between iodine and the .sup.1 .DELTA. metastable state of oxygen.
The recent development of systems capable of generating and amplifying coherent electromagnetic energy in the optical frequency range has created a considerable amount of interest in utilizing such systems for a variety of military, navigation, communication and heating applications. In order to produce the desired energy, or lasing action, the systems employ an optically active component from which the coherent electromagnetic energy is extracted by means of a phenomenon called population inversion. The optically active component possesses an unstable energy state capable of releasing photons as they decay to lower energy states.
The optically active compound may be a solid, liquid or gas. The gas laser, the subject matter of which concerns this invention, is generally categorized as being chemical, electric discharge, optically pumped, or gas dynamic depending on the manner by which the optically active component achieves the requisite population inversion. Chemical lasers achieve population inversion by direct generation or pumping of higher energy states through the mechanism of a chemical reaction. A critical portion of our device is that it populates electronically excited states rather than vibrationally excited states. It is the first chemically pumped laser to do so. As such it is the shortest wavelength device yet devised. Electric discharge lasers achieve their population inversion by pumping the higher energy state by means of an electric current while gas dynamic lasers achieve population inversion by reducing the population level of a lower energy vibrational state of a hot gas in thermal equilibrium by reason of a rapid cooling caused by a supersonic aerodynamic expansion.
In general, the technique for generating a laser action by means of a chemical reaction is achieved by the resonant transfer of energy through a reaction between an energizing reactant, such as vibrationally excited nitrogen, and a lasing reactant such as carbon dioxide. Other gasous products, such as nitrous oxide, carbon dioxide, helium, hydrogen, fluorine and mixtures thereof are known for their lasing action. For example, the diffusion of hydrogen into a supersonic jet flow containing fluorine reacts chemically to provide a sustained flow of a vibrationally excited gaseous product having the necessary population inversion and lifetime required for lasing. The vibrationally excited gas flows into an optical laser cavity where the lasing action is actually generated.
The chemical lasers presently available in the art operate on rotational-vibrational transitions within a single electronic state. With this invention, however, it has been found that a lasing action can be achieved by chemically pumped electronic transitions. This represents a new class of lasers. The operation is continuous and laser excitation is obtained entirely from chemical energy. Energy transfer takes place from electronically excited molecular oxygen to atomic iodine. This is the first atomic iodine laser operating at 1315 nanometers wavelength with continuous power. The system of this invention provides continuous lasing at shorter wavelengths than produced by presently known chemical lasers.
Accordingly, the primary object of this invention is to provide a system for the production of a continuous wave lasing action.
Another object of this invention is to provide a lasing system in which the requisite population inversion is accomplished through the medium of a chemical reaction with no external power source required.
Still another object of this invention is to provide a lasing system that operates at short wavelengths.
A further object of this invention is to provide a chemically pumped electronic transition laser.
Still a further object of this invention is to provide an atomic iodine laser that operates at 1315 nanometers wavelength with continuous power.
The above and still further objects and advantages of the present invention will become more readily apparent upon consideration of the following detailed disclosure thereof when viewed in conjunction with the accompanying drawing.